Ecological Succession Change in an Ecosystem

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Ecological Succession Change in an Ecosystem
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What is Succession?

• Natural, gradual changes in the types of species
  that live in an area can be primary or
  secondary.

• The gradual replacement of one plant community by
  another through natural processes over time.

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Primary vs. Secondary Succession

• Primary
• The gradual growth of an ecosystem in an area
  lacking soil over a long period of time.
• Often takes several hundred to a few thousand
  years.

• Secondary
• Occurs when a plant community has been destroyed
  without severe disturbance to the soil.
• Typically much faster but not always.

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Primary Succession

• Begins in a place without any soil
• Sides of volcanoes
• Landslides

• Flooding
• Starts with the arrival of living things such as
  lichens that do not need soil to survive.
• These organisms like lichens are called PIONEER
  SPECIES.

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Primary Succession

• Soil starts to form as lichens and the forces of
  weathering and erosion help break down rocks into
  smaller pieces and move them to new areas.

• When lichens die, they decompose, adding small
  amounts of organic matter to the rock to make
  soil.

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Primary Succession

• Simple plants like mosses and ferns can grow in
  the new soil.

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Primary Succession

• The simple plants die, adding more organic
  material to the soil.
• The soil layer thickens. Grasses, wildflowers,
  other plants, and small animals begin to take
  over.

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Primary Succession

• As grasses and other plants die, they add more
  nutrients to the soil.
• Shrubs, tress and larger animals can now survive
  in the area.

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Primary Succession
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Secondary Succession

• Secondary Succession is initiated by an event.
• For example a forest fire, hurricane, or
  harvesting a crop
• The already-established ecosystem is reduced or
  drastically changed.

• Secondary Succession occurs on land with
  preexisting soil.
• The process is similar to Primary Succession
  thereafter.

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Secondary Succession